#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int jump(int n)
{
	if (n == 1)
	
		return 1;
	
	else if (n == 2)
	
		return 2;
	
	else
	
		return jump(n - 2) + jump(n - 1);
	
}
int main()
{
	int i = 0;
	while (scanf("%d", &i))
	{
		int j = jump(i);

		printf("%d\n", j);
	}
	return 0;
	
}